At present, touch panel technology generally includes following several types: resistive type, capacitive type, optical type, electromagnetic type, ultrasonic type, and in-cell type liquid crystal panel (which includes resistive type, capacitive type, and optical type). In a display device with an in-cell type photosensitive touch panel, it uses leakage current differences caused by different light irradiation intensity as a condition whether turning on a light-sensing component in the in-cell type photosensitive touch panel, so as to judge whether the in-cell type photosensitive touch panel has been touched.
For example, the light-sensing component includes a thin film transistor, and so on. When the light-sensing component is touched by a finger, irradiated by ambient light, and touched by a light pen, leakage currents of the thin film transistor are corresponding to a first current value, a second current value, and a third current value, respectively. Therefore, when the light irradiation intensity received by the light-sensing component is higher, the leakage current Ids of the thin film transistor is greater, that is to say, the first current value is less than the second current value, and the second current value is less than the third current value. Then, a charge difference generated by the different leakage currents of the thin film transistor is converted into an output voltage by an integrator, so as to judge whether is touched according to the value of the output voltage.
The above-mentioned judging process only employs one thin film transistor as an example. However, a touch panel can includes ten thousand light-sensing components, and current-voltage curves of each thin film transistor in the touch panel may be different. As shown in FIG. 1, a current-voltage curve of a first thin film transistor TFTA is different from that of a second thin film transistor TFTB. For example, in the conditions with light irradiation and no light irradiation, a same gate voltage Vgs (e.g., −3 volts), for the first film transistor TFTA, it can effectively judge whether the first film transistor TFTA is touched. However, for the second film transistor TFTB, a misjudgment result may be generated. Therefore, based on difference characteristics of the different thin film transistors, the light-sensing component may generate misjudgment results.